One means for reducing the overall diameter of a fuel injector comprises using hermetic laser welds instead of O-ring seals at certain internal joints. This allows certain individual parts to be of smaller diameters.
Since the diameter of the fuel inlet tube of a top-feed fuel injector is sized for use with a particular standard-sized O-ring seal that seals the fuel inlet tube to a cup, or socket, of a fuel rail, a reduction in its diameter is apt not to be cost effective since a non-standard-sized O-ring would have to be tooled for it. A reduction in the overall diameter of the electromagnetic coil assembly can be accomplished albeit at the expense of a modest non-objectionable increase in overall length for the coil assembly in order to maintain fuel injector performance. The fuel inlet tube still passes into a central through-hole of the fuel injector's electromagnetic coil assembly.
The electromagnetic coil assembly of a typical fuel injector has a pair of formed metal electrical terminals via which it electrically connects with an electric control circuit for selectively energizing the assembly's electromagnetic coil to operate the fuel injector. These terminals have standardized blade sizes, and costwise it may be preferable to maintain these standardized blade sizes in a reduced diameter electromagnetic coil assembly. Each terminal typically mounts on an end wall of a non-ferromagnetic bobbin (plastic, typically) on which the electromagnetic coil is disposed and which contains the central through-hole into which the fuel inlet tube passes. The terminals are circumferentially spaced apart. One end of each terminal is electrically joined to a respective termination of the wire that is wound on the bobbin to form the electromagnetic coil and that end of the terminal is embedded in the bobbin end wall while the remainder of the terminal, including a standard-sized blade at the opposite end, is exposed. These exposed blades are disposed spaced apart, parallel and side-by-side, within a surround portion of the fuel injector's non-metallic plastic overmold cover, to form an electrical connector plug adapted for mating engagement with a mating connector containing the mating terminals that lead to the electric control circuit for operating the fuel injector.
Each terminal is of uniform thickness and of rectangular transverse cross section throughout its length, although the width may differ in different sections along the length. Not only are the sections of the terminals that are embedded in the bobbin end wall circumferentially spaced apart about the bobbin through-hole and the portion of the fuel inlet tube that is disposed coaxially therein, but their flat widthwise surfaces that generally face the fuel inlet tube are disposed in a common imaginary plane.
The present invention relates to a novel construction for these terminals for better accommodation with a reduced diameter electromagnetic coil assembly. The invention arises from the observation that when the diameter of the electromagnetic coil assembly is reduced, there is also reduced clearance between the terminals and one or more electrically conductive parts that are in the vicinity of the electric terminals of the coil assembly, for example clearance to a metal housing that is disposed over the coil assembly to form a portion of a stator structure that is associated with the coil assembly.
The invention places those portions of the terminals that are embedded in the bobbin end wall at an angled relationship to each other such that their flat, planar, widthwise surfaces that face the fuel inlet tube are disposed in respective non-parallel planes. Such orientation increases clearance of the terminals to any proximate electrically conductive part, or parts, when compared with a prior fuel injector using the same sized and shaped parts except for the widthwise surfaces that face the fuel inlet tube being in a common plane in the prior fuel injector. Thus, one of the advantages of the invention resides in reducing the risk of shorting a terminal to a nearby electrically conductive part of a reduced diameter fuel injector. Yet, the exposed blades that are to mate with respective mating terminals of the mating connector that leads to the electric control circuit, remain disposed spaced apart, parallel and side-by-side within the non-metallic surround so that the mating connector and its terminals can continue to be of standardized dimensions throughout, and thus avoiding the necessity of re-tooling those parts to accommodate the new fuel injector terminal configuration.
Various features, advantages and the inventive aspects will be seen in the ensuing description and claims which are accompanied by drawings that disclose a presently preferred exemplary embodiment of the invention according to the best mode contemplated at the present time for carrying out the invention.